DAS Introduction to Genetics Introduction to Animal Husbandry

DAS Introduction to Genetics Introduction to Animal Husbandry 2017

What is Genetics • It is the science that deals with the study of heredity and variation • Word GENETICS came from Genesis meaning beginning HEREDITY: Transmission of traits from parents to offspring VARIATION: Dissimilarities / differences

Conti… • Involves the study of structure and function of genes • Differences in organisms are due to differences in genes which have result from • • • Evolutionary process of mutation Genetic recombination Selection

Conti… • Genetic information directs • Cellular functions • Determines an organism’s external appearance • Links generations in every species • Knowledge of genetic concepts also helps us to understand other disciplines of biology like; • Molecular biology • Cell biology • Physiology • Evolution etc.

Charles Darwin • Proposed pangenesis • Pangenesis ? • It is a hypothetical mechanism (1868) for heredity, in which he proposed that each part of the body continually emitted its own type of small organic particles called gemmules that aggregated in the gonads, contributing heritable information to the gametes

Who duplicated the work of Mendel • Around 1854, Mendel began to research the transmission of hereditary traits • Hugo de Vries, Carl Correns and Erich von Tschermak-Seysenegg each independently duplicated Mendel's experiments and results in 1900, finding out after the fact, allegedly, that both the data and the general theory had been published in 1866 by Mendel

DNA and Genomic Era • 1944: The Avery–Mac. Leod–Mc. Carty experiment isolates DNA as the genetic material (at that time called transforming principle) • 1950: Erwin Chargaff determined the pairing method of nitrogenous bases • 1952: an X-ray diffraction image of DNA taken by Raymond Gosling, a student supervised by Rosalind Franklin • 1953: DNA structure is resolved to be a double helix by Rosalind Franklin, James Watson and Francis Crick • 1972: Walter Fiers and his team were the first to determine the sequence of a gene: the gene for bacteriophage coat protein • 2001: First draft sequences of the human genome are released by human genome project

Branches of Genetics • Cytogenetics Deals with the physical basis of heredity (cell) • Population Genetics Deals with the transmission of traits with a large group of individuals with a passage of time • Molecular Genetics Chemical basis of heredity Advanced field of genetics • Genomics The branch of genetics concerned with the structure, function, evolution, and mapping of genomes of an organism

Eugenics • Study and control of various means of improving human heredity characters has been termed as “Eugenics” • Positive Eugenics is concerned with the enrichment of human populations by facilitating an increase or at least guarding against decrease in favorable traits • Negative Eugenics attempts to curtail defective heredity traits by limiting or preventing their reproduction

Conti… • Nutrogenomics: Study of effect of different nutrients or nutrition on gene expression • Behavioral Genetics Study of the behavior of an organism • Genetic Engineering Genetic engineering (GE) is the modification of an organism's genetic composition by artificial means, often involving the transfer of specific traits, or genes, from one organism into a plant or animal of an entirely different species.

Application of the Genetics

Human & Society • An estimation of about 2000 genetics diseases in humans • Ø Ø Ø Many diseases and abnormalities have genetic basis, e. g Hemophilia Some type of diabetics, Hemolytic icterus (an anemia), Some form of deafness Blindness (some types)

Conti… • Recognition of these inherited nature is important for anticipation of their future possible occurrence in given family so that preventive measures can be taken • Chromosomal analysis can be used to detect a large no. of abnormalities in fetus, newborn, child and adult • Amniocentesis - amniotic fluid and fetal cells taken from pregnant women are analyzed for genetic disorders

Conti… v. Genetics can be used in prevention of non-infectious abnormalities e. g. Xanthoma Tuberosum It is characterized by appearance of numerous nodules and tumors in the body and may involve then heart or blood vessels some time with fatal results These nodules develop due to an excess of cholesterol in the blood If the patient knows then what can somebody do ? Avoid cholesterol in diet and can check after intervals

Genetic Counseling The process by which patients or relatives at risk of a disorder that may be hereditary are advised of the consequences of the disorder The probability of developing or transmitting it, and of the ways in which this may be prevented, avoided or ameliorated Genetic education and pre-marital medical tests can play a role reduce genetic abnormalities in humans

Potentials of Genetic Counseling • Today clinical tests can be carried out on heterozygotes for many hereditary disorders • After obtaining such information on both potential parents the risk of producing an afflicted offspring can be estimated • Family histories may indicate a high risk of genetic diseases • Such tests are now available for most cytological and over 70 other heredity anomalies e. g Amniocentesis

Conti…. • In case of abnormal infant, family may opt for termination of pregnancy if law permits (involves moral and religious considerations) • Families may decide to forego having children of their own and rely upon adoption • In such a way many tragedies can be avoided

Legal Applications • Many court cases rely o geneticists for valuable testimony • Questions of disputed parentage • Baby mix up in hospitals • Custody of children • Estate inheritance These are some of the legal problems on which courts may turn for scientific solutions